1. Field of the Invention
This invention relates to a control rod assembly that transmits motion from one connected device to another. More particularly, this invention pertains to such devices that include means for adjusting the length of the control rod.
2. Description of the Prior Art
Devices that transmit motion from one movable component to another, such as cable assemblies, generally provide an attachment on a conduit containing the cable for connecting the conduit to a support structure, and a cable extending from each end of the conduit. Whether the connecting devices are cable assemblies or rods capable of carrying loads in either direction, it is often necessary to adjust the effective length of the assembly that extends between the support structure and one end of the cable or between the ends of the rod assembly attached to the movable components, while the assembly is being installed.
Where a cable assembly is used for this purpose, the length of the cable that extends from the end of the conduit may be changed by altering the length of the path over which the conduit extends. Usually the paths are curves or bends whose lengths are reduced by increasing the length of the conduit that extends beyond the mounting points of the assembly. However, once the assembly is adjusted, it is usually difficult to release the locking member from engagement with ratchet teeth on a fitting that is secured to the conduit in order to reposition or readjust the assembly for repair and maintenance. U.S. Pat. Nos. 3,572,159; 4,669,330; 4,658,668 describe cable assemblies of this type. A frequent disadvantage that arises in cable assemblies is the difficulty required to vary the force used to set and maintain the length of the cable assemblies.
Where adjustable length rod assemblies are used to transmit motion between members connected to the rod assembly, the prior art has employed a threaded mechanical connection biased by the coiled spring and retained in position by a set screw driven against the rod assembly and held on a trunnion, whose position along the length of the rod is adjustable in accordance with the position where the set screw engages the rod. Where this technique is employed, high extraneous randomly directed loads caused by the process of wrench tightening the set screw are introduced to the rod assembly during the process of establishing its length. As a result, an assembly operator is required to carefully adjust and check the length of the rod assembly. U.S. Pat. No. 4,422,242 describes and illustrates a throttle valve linkage adjustment gauge wherein a rod assembly 10 is attached to the gauge by a pin and grommet connection. It is preferred that some other technique than the use of wrench tightening requiring high torque be used to establish the length of the rod.